Modern computers/workstations use various forms of pointing devices to facilitate the positioning of a cursor on the display screen. A commonly known form of such a pointing device is the "mouse". The mouse is a hand-held device that, when moved about a work surface (e.g., a desk-top), causes a corresponding movement of a cursor on the computer's video display. Such mouse-type systems are disclosed by U.S. Pat. Nos. 3,892,963; 3,541,521; 4,464,652 and 4,546,347.
The mouse is a very popular cursor-pointing device, particularly for graphics-interactive applications; e.g., CAD (Computer Aided Design), where frequent and precise cursor positioning is essential.
The mouse is most precise as a pointing device when the distance that the cursor is moved on the display is the same as or less than the distance that the mouse is moved on the work surface.
A disadvantage of common mouse cursor control devices found in prior art is the fact that the user is distracted by interruptions in cursor control when mouse travel exceeds the operative area available for reliable mouse operation; e.g., the mouse runs off the edge of its pad or collides with other desk-top objects in the vicinity. Furthermore, the re-centering of the mouse within its operative area without disturbing the position of the cursor requires the mouse to be lifted off the work surface; such frequent action causes a significant increase in operator hand/arm fatigue. As the display area of modern computer/workstations increase in size, the above-mentioned disadvantages grow worse and the following problems are encountered: 1) where the mouse's operative area (domain) is simply increased proportional to the larger display area, valuable work space (desktop) is displaced by the larger mouse domain and even more important is the fact that operator hand/arm fatigue is increased because of the resulting longer movements of the mouse; 2) where the mouse domain is kept to a more practical (smaller) size, the distance that the cursor can be moved in a particular direction by a single movement (stroke) of the mouse is limited; therefore, longer cursor movements require multiple mouse strokes in a particular direction that increase operator hand/arm fatigue caused by the necessity to lift the mouse off the work surface during the retrace of each of the multiple strokes of the mouse; 3) where a ratio of mouse movement to cursor movement is chosen such that the cursor range is significantly larger than the mouse range, cursor precision suffers; that is, the cursor becomes overly sensitive or jumpy in response to small mouse movements, causing precise cursor placement to be very difficult or impossible.
Clearly, for larger display applications, it would be advantageous to provide means to enable mouse operation to efficiently move the cursor to any zone of a large display, yet enable the mouse's operative area to remain relatively small while retaining an ideal ratio of mouse movement to cursor movement for precise cursor positioning. Furthermore, it would be advantageous for such a means to extend the effectiveness of the host system's existing mouse system and, therefore, to not require replacement or modification of the existing mouse so that implementation of such means may be most economical. Furthermore, it would be advantageous for such a means to be applicable to any type of mouse (e.g., mechanical, optical) or any type of mouse/host interface (e.g., parallel, serial). Furthermore it would be advantageous for the implementation of such means to be transparent to any existing system operation; that is, implementation should not require any modification of any of the host system's existing hardware or software. Furthermore, installation and operation of such implementation should be simple.
As will be disclosed below, the present invention provides an improved cursor control system that is used in conjunction with the common mouse-type cursor control system to extend the effectiveness of the operation of the attached mouse to overcome the above-mentioned disadvantages of the prior art and to provide the above-mentioned advantages, particularly where used with display systems with relatively large viewing area.